Metal rectifier



1948- E. AQRICHARDS 2,447,534

' METAL RECTIFIER Filed June 15, 1944 2 Sheets-Sheet 1 F/G.3 B

I I c M c 1 F L H Lil 2i -c I inventor I E. .A. RICHARDS METAL RECTIFIER 2 Sheets-Sheet 2 Filed June 15, 1.944

F/GS

Patented Aug. 24, 1948 Edward Arthur Richards, London, England, as-

signor, by mesne assignments, to International Standard Electric Corporation,

N ew' York,

N. Y., a corporation of Delaware Application June 15, 1944, Serial No. 540,375 In Great Britain July 15, 1943 4 Claims. 1

This invention relates to improvements in metal rectifiers of the disc or plate type, for example the well known selenium disc type of. rectifier, and has for one of its objects to provide an improved construction or assembly of such rectifiers.

Metal rectifiers of the disc or plate type are usually assembled by threading the discs and suitable spacing washers on an insulated spindle with threaded ends and securing the whole unit by nuts at each end of the spindle. pressure produced by over-tightening the nuts may cause damage to a disc or discs and it is particularly important to avoid this when a large number of individual discs is connected in parallel, since a breakdown in one disc may shortcircuit the whole assembly. Under these conditionsvery heavy currents may flow and cause damage to the other arms of the rectifier.

According to a feature of the present invention the spindle is replaced by a spring whichis designed so that the predetermined pressure which it exerts on the discs when assembled is suifiicient to provide good electrical contact but not great enough to cause damage to the discs. The above and other features of the invention will be better understood by reference to the accompanying drawings in which:

Fig. 1 is'a front elevation of a rectifier element and associated bus-bars forming part of a large as the power supply for electrolytic processes.-

Rectifier discs AA are assembled in pairson a bar or plate B which may carry a number of pairs similar to those shown. The rectifier discs may be of the type in which a metal base plate is coated on one side with a layer of selenium to which, after suitable heat treatment, a counterelectrode'of metal alloy is applied. Preferably, they are also of the so-called centre-contact type in accordance with U. S. Patent No. 2,314,104.

The discs are mounted with the base plates adjacent to the bar B so that when.the counterelectrodes are connected together the two discs Excessive the discs which are mounted upon it.

Connection is made to the counter-electrode surface by the shaped washers CC and the current is conducted to these washers by thin metal of the tion of theinvention to the more conventional strips D. These strips are formed with a constriction at E so that they act as a fuse in case a disc should develop a short-circuit in service.

A collar F through which a pin G is inserted and secured at each end anchors one end of the spring H. In assembling a pair of discs an insulating tube K is inserted in the hole in the bar B and a disc A, washer 0, connecting strip D and collar F are slipped on the tube on one side of the harm the order stated. A disc A, washer C, connecting strip D and washer J are then placed on the tube on the opposite side of the bar. The hook L of the spring then projects through the tube so that it canbe engaged by a suitable tool in order to extend the spring and allow the pin M to be inserted to complete the assembly. This pin is cranked as shown to centralize the spring and prevent the pin from working .out owing to vibration. The outer ends of the connection strips D are secured by, and make contact with, a bolt N and bus-bar N which is insulated from the bar B and serves as the common connection to the counter-electrode surfaces 01 the discs.

It will be seen that the pressure exerted on the contact area of the discs is limited by the design of the spring and the thickness of the various members and cannot exceed the value predetermined by these factors.

. If desired, two or more discs may be assembled in series on either side of the bar without affecting the principle of the arrangement. A

longer tube and spring would, of course, be

necessary to allow for the thickness of the'additional discs and spacing washers.

Figs. 4 and 5, for example, show the applicatype of rectifier assembly comprising a number of rectifier discs assembled in series. In this case the rectifier discs A are assembled on' the insulating tube K together with the usual spacing washers 0 connecting tags P and insulating washers Q at the ends, and electrical contact between the members is maintained by the tension of the spring H acting through the end collars F and J.

What is claimed is:

1. A metal rectifier assembly comprising a counter electrode surfaces in parallel, said discs,

washers and fusible metal connections being as- 4 4. In a dry disc rectifier unit oi. the type that comprises a plurality of disc rectifier elements and spacer members assembled under tension in stacked Y coaxial relationship upon mounting means extending through centrally located openings in the disc elements and spacer members,

sembled on the metal bar and maintained in electrical contact by means of a helical spring passing through an aperture in said bar.

2. A metal rectifier assembly as set forth in claim 1, in which said discs and said contact washers are threaded on a tube of insulating material and said spring extends through said tube and is anchored at its ends to cross members engaging thrust collars for transmitting the spring pressure to said contact washers and said discs.

3. A metal rectifier assembly as set forth in claim 1, in which said discs and said contact washers are threaded on a tube of insulating material and said spring extends through said tube and is anchored at its ends to cross members engaging thrust collars for transmitting the spring pressure to said contact washers and said discs. said cross members comprising diametrically arranged pins, one of which is coupled to one end of said spring and secured in a thrust collar, whereas the other pin is cranked to be self centering on the other thrust collar when the said spring is tensioned.

the improved means for maintaining said elements under predetermined uniform constant tension that comprises a helical spring positioned within an axially extending opening in said mounting means and caps connected to the opposite ends of the spring cooperating with the terminal rectifier elements whereby said elements are spring-urged toward each other. I

EDWARD ARTHUR RICHARDS.

nsranancss crran The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date a 380,184 Celce Mar. 2'7, 1888 1,462,925 Wilburger July 24, 1923 1,898,321 Btrobel Feb. 21, 1933 2,327,511 De Lange et al Aug. 24, 1943 2,338,890 Zierdt Jan. 11. 1944 2,378,411 Kotterman June 19, 1945 FOREIGN PATENTS Number Country Date 114,329 Australia Dec. 2, 1941 

